Genetic drift is defined as random changes in allele frequencies in a population. It occurs in all populations that are not infinitely large and has a particularly strong effect on small populations over several generations. Because genetic drift is a random rather than deterministic process like natural selection, students often have a difficult time understanding and appreciating its role in evolution.

This simple exercise offers an active learning approach by simulating the founder effect and bottleneck effect (two examples of genetic drift) using M&Ms. A worksheet with full instructions, examples of discussion questions and data sheets is available to download in full from here.